To improve image quality captured in a dim environment, an application of an invisible light is taken into account for most cameras. Known applications are mainly divided into two types: single lens and double lens.
For the single lens, one dual lens or one full-spectrum lens that allows an infrared light to pass through is applied. The image quality in night may be improved, but a color distortion of the image in day may be caused because of absorption of infrared energy, for example, a black cloth will became reddish in the image.
For the double lens, one camera is equipped with two types of lenses. In a strong light environment (for example in day), an ordinary lens that allows a visible light to pass through is used; and in a weak light environment (for example in night), the dual lens or the full-spectrum lens that allows the infrared light to pass through is used. According to the above methods, the image color in an ordinary environment may be reproduced and the image quality in night may be improved. But it is required to switch between the two lenses in different environments, which makes an usage of the lens complicated, a cost over high and the usage unstable.
A Bayer matrix is currently used in the above lens. FIG. 1 shows a 4*4 Bayer matrix unit. As shown in FIG. 1, a pixel block A comprises pixels 1′, 2′, 3′ and 4′. R, G and B represent a red filter, a green filter and a blue filter respectively. The blue filter B is disposed in the pixel 1′, the green filters G are disposed in the pixel 2′ and 3′ respectively, and the red filter R is disposed in the pixel 4′.